added navigation bar feature

check it out
closed:
![screen shot 2013-05-29 at 8 43 35 pm](https://f.cloud.github.com/assets/407586/582600/3ec2d91a-c8c2-11e2-8f2f-43e2883e75b6.png)

open:
![screen shot 2013-05-29 at 8 43 49 pm](https://f.cloud.github.com/assets/407586/582601/3ecbeb7c-c8c2-11e2-999c-180e6191a7fe.png)